Pico
A reverse proxy to connect to external networks (tunnelling)
Infrastructure
What Is Piko?
Piko is a reverse proxy that provides a secure way to connect to services that aren’t publicly routable, known as tunneling. Instead of sending traffic directly to your services, your upstream services open outbound-only connections (tunnels) to Piko, then Piko forwards traffic to your services via their established connections.
Piko has two key design goals:
- Built to serve production traffic by running as a cluster of nodes for fault tolerance, horizontal scaling and zero-downtime deployments
- Simple to host behind a HTTP(S) load balancer on Kubernetes
Therefore Piko can be used as an open-source alternative to Ngrok.
Such as you may use Piko to expose services in a customer network, a bring your own cloud (BYOC) service, or to connect to user devices.
Reverse Proxy
In a traditional reverse proxy, you configure routing rules describing how to route incoming traffic to your upstream services. The proxy will then open connections to your services and forward incoming traffic. This means your upstream services must be discoverable and have an exposed port that's accessible from the proxy.
Whereas with Piko, your upstreams open outbound-only connections to the Piko server and specify what endpoint they are listening on. Piko then forwards incoming traffic to the correct upstream via its outbound connection.
Therefore your services may run anywhere without requiring a public route, as long as they can open a connection to the Piko server.
Endpoints
Upstream services listen for traffic on a particular endpoint. Piko then manages routing incoming connections and requests to an upstream service listening on the target endpoint. If multiple upstreams are listening on the same endpoint, requests are load balanced among the available upstreams.
No static configuration is required to configure endpoints, upstreams can listen on any endpoint they choose.
You can open an upstream listener using the
Piko agent, which supports
both HTTP and TCP upstreams. Such as to listen on endpoint my-endpoint and
forward traffic to localhost:3000:
# HTTP listener.
$ piko agent http my-endpoint 3000
# TCP listener.
$ piko agent tcp my-endpoint 3000
You can also use the Go SDK
to listen directly from your application using a standard net.Listener.
HTTP(S)
Piko acts as a transparent HTTP(S) reverse proxy.
Incoming HTTP(S) requests identify the target endpoint to connect to using
either the Host header or x-piko-endpoint header.
When using the Host header, Piko uses the first segment as the endpoint ID.
Such as if your hosting Piko with a wildcard domain at *.piko.example.com,
sending a request to foo.piko.example.com will be routed to an upstream
listening on endpoint foo.
To avoid having to set up a wildcard domain you can instead use the
x-piko-endpoint header, such as if Piko is hosted at piko.example.com, you
can send requests to endpoint foo using header x-piko-endpoint: foo.
TCP
Piko supports proxying TCP traffic, though unlike HTTP it requires using either Piko forward or the Go SDK to map the desired local TCP port to the target endpoint.
Piko forward listens on a local TCP port and forwards connections to the configured upstream endpoint via the Piko server.
Such as to listen on port 3000 and forward connections to endpoint
my-endpoint:
piko forward 3000 my-endpoint
Note unlike with HTTP, there is no way to identify the target endpoint when connecting with raw TCP, which is why you must first connect to Piko forward instead of connecting directly to the Piko server. Piko forward can also authenticate with the server and forward connections via TLS.
You can also use the Go SDK
to open a net.Conn that's connected to the configured endpoint.
Design Goals
Production Traffic
Piko is built to serve production traffic by running the Piko server as a cluster of nodes to be fault tolerant, scale horizontally and support zero downtime deployments.
Say an upstream is listening for traffic on endpoint E and connects to node N. Node N will notify the other nodes that it has a listener for endpoint E, so they can route incoming traffic for that endpoint to node N, which then forwards the traffic to the upstream via its outbound-only connection to the server. If node N fails or is deprovisioned, the upstream listener will reconnect to another node and the cluster propagates the new routing information to the other nodes in the cluster. See How Piko Works for details.
Piko also has a Prometheus endpoint, access logging, and status API so you can monitor your deployment and debug issues. See observability for details.
Hosting
Piko is built to be simple to host on Kubernetes. This means it can run as a cluster of nodes (such as a StatefulSet), supports gradual rollouts, and can be hosted behind a HTTP load balancer or Kubernetes Gateway.
Upstream services and downstream clients may connect to any node in the cluster via the load balancer, then the cluster manages routing traffic to the appropriate upstream.
See Kubernetes for details.
Getting Started
See Getting Started.
How Piko Works
See How Piko Works.
Support
Use GitHub Discussions to ask questions, get help, or suggest ideas.
Docs
See Wiki.
Contributing
See CONTRIBUTING.
License
MIT License, please see LICENSE for details.